Heretofore, a previously proposed magnetic recording and/or reproducing apparatus has employed the ID-1 format data recorder (ANSI x34.175-1990 19 mm Type (D-1 Recorded Instrumentation), in which helical recording tracks are sequentially formed on a magnetic tape to record and reproduce desired data with high density.
FIG. 11 illustrates a magnetic tape 1 that includes a plurality of tracks recorded by the ID-1 format data recorder. Magnetic tape 1 is wrapped around a rotary drum and rotated at a predetermined speed. The magnetic tape 1 is run at a predetermined speed, so that recording tracks TRs (TR1, TR2, TR3, TR4, TR1, TR2, . . . ) are helically and sequentially formed by a magnetic head mounted on the rotary drum. In this manner, desired data are recorded onto recording track TR1.
Also at this time, the data recorder forms recording tracks TA, CTL, and TC, which extend along the longitudinal direction of magnetic tape 1. Recording track TA is located at the upper portion of magnetic tape 1, and recording tracks CTL and TC are located at the lower portion of magnetic tape 1. The data recorder records the track set ID of the recording track TR in the recording track CTL.
The track set ID contains absolute position information, and it is recorded from the beginning of the magnetic tape 1, at locations that are in between the predetermined synchronizing signals that correspond to each set of 4 recording tracks (TR1 . . . TR4).
The recording tracks TA, CTL, and TC contain user management data which permits high density data recorded on magnetic tape 1 to be searched easily.
In the data recorder, when information is recorded on the recording track TR, the recorded information includes a parity code of a product code. The parity code is used for error detection and correction, thereby enhancing the reliability of data recorded on and reproduced from magnetic tape 1.
That is, as shown in FIG. 12, after the data recorder takes in a predetermined unit of data (comprising 36,108 bytes and hereinafter designated as data field DATA), it divides the data field DATA into 306 blocks, and adds to each block a Reed-Solomon error detecting and correcting code.
Furthermore, the data recorder divides each block into a first and second field, FIELD0 and FIELD1, and then adds a Reed-Solomon error detecting and correcting code (designated as C1) so as to orthogonalize with the C2 code in each of the fields FIELD0 and FIELD1.
Thereby, in the data recorder, the reproduced data are error-corrected by using the C1 and C2 codes, thereby improving the bit error rate.
Further, when the data field DATA, including the C1 and C2 codes, is recorded onto the magnetic tape 1, the data recorder interleaves the data field DATA in recording track TR. Thereby, the data field DATA can be reproduced reliably, even in the presence of a drop-out.
In other words, in the data recorder, assuming that the data field DATA has been supplied as a sequence designated by arrows a1, a2, . . . , an-1, an, an+1, an+2, . . . ax-1, and ax, the data field DATA is recorded in a different sequence as shown by arrows b1, b2, . . . bn-1, bn, in order to interleave the above data field DATA.
Furthermore, the data recorder adds to each data field DATA a synchronizing signal SYNC and a sync block data ID (hereinafter referred to as "sync block"). During the recording of the data field DATA, the data recorder also adds a preamble and a postamble to the data field DATA.
During reproduction of magnetic tape 1, the synchronizing signal SYNC, the sync block data ID, and the data DATA are reproduced with reference to track sync data included in the preamble, which allows the magnetic recording and/or reproducing apparatus to deinterleave the data field DATA with reference to the above synchronizing signal SYNC and the sync block data ID.
If a drop-out occurs in magnetic tape 1, this deinterleave-processing prevents errors that exceed the error-correcting capability of the C1 and C2 codes from concentrating on one part of the reproduced data.
By reproducing, in this manner, data arranged in the ID-1 format, a bit error rate of about 10.sup.-10 can be achieved, which is satisfactory for practical use as a data recording and/or reproducing apparatus mainly for measurement.
If this bit error rate can be improved to about 10.sup.-15, then the magnetic recording and/or reproducing apparatus can store the data of computer systems used at banks, etc., for example, thus expanding the utility of this type of data recorder.
Further, since this type of data recorder can record high-density data, an improvement of the bit error rate will facilitate the management of the magnetic tape by collectively recording a plurality of files onto a magnetic tape.
However, the drawback to the collective recording of a plurality of files in this manner is that the search for particular files become difficult.
One possible solution is to retrieve data by performing a high-speed search on the high-density tape. However, since the magnetic head helically crosses respective recording tracks, the desired data cannot be reliably reproduced when high-speed searching is used. Thus, this method of retrieving data is insufficient for the previously proposed data recorder.